The overall goals of the proposed project are 1) to develop Dr. Helane Wahbeh into an independent complementary and alternative physician researcher;and 2) to conduct a clinical research trial in mind-body medicine evaluating mechanisms of action. Dr. Wahbeh will develop her knowledge base, experience and skill in four key areas through mentored training: 1) design and implementation of randomized controlled trials;2) neuroscience and collecting and analyzing electrophysiological data, 3) biostatistics, and 4) mindfulness meditation. The long term goal of the research training plan is to discover the mechanism of action of meditation therapy and thus improve its effective use. As a first step, the study will serve as a model study to carefully separate the mechanistic pathways of meditation components. The primary objectives of the proposed study are to evaluate two common parts of meditation, mindfulness and slowed breathing, and to characterize the mechanism by which they may affect clinical outcomes. In a randomized controlled trial, 100 veterans with PTSD will be allocated one of four groups 1) mindfulness meditation, 2) slowed breathing, 3) mindfulness meditation and slowed breathing, or 4) a sitting quietly control group. The participants will have one 20 minute laboratory session each week for six weeks with 20 minutes of daily home practice between sessions. Measures will be assessed before and after the intervention period. The specific aims are to assess the mechanism of action of meditation by observing differences among groups on measures within three physiological systems: the autonomic nervous system, frontal cortex activity, and the hypothalamic-pituitary-adrenal (HPA) axis. We hypothesize that slowed breathing alone will affect autonomic nervous system measures and reduce hyper-arousal symptoms, whereas mindfulness meditation will influence cognitive function through frontal cortex activity and decreased intrusive thoughts. We predict that the combination of slowed breathing with the mindfulness component will show both autonomic and frontal cortex activity effects and that all interventions will influence the downstream pathway of HPA axis activity. PUBLIC HEALTH RELEVANCE: The study is important to public health because meditation is widely used without knowing exactly how it works. The study will help clinicians prescribe different types of meditation therapy to appropriate patient groups more effectively and adapt pieces of meditation therapy to match the illness being treated. Also, further clinical research is needed on treatments for veterans with PTSD, whom are a rapidly growing group.